src/worker/WorkerSet.ts

   1 // Partial Copyright Jerome Benoit. 2021-2023. All Rights Reserved.
   2
   3 import { EventEmitter } from 'node:events';
   4 import { SHARE_ENV, Worker } from 'node:worker_threads';
   5
   6 import type { ThreadPoolOptions } from 'poolifier';
   7
   8 import { WorkerAbstract } from './WorkerAbstract';
   9 import { WorkerConstants } from './WorkerConstants';
  10 import {
  11   type SetInfo,
  12   type WorkerData,
  13   WorkerMessageEvents,
  14   type WorkerOptions,
  15   type WorkerSetElement,
  16   WorkerSetEvents,
  17 } from './WorkerTypes';
  18 import { sleep } from './WorkerUtils';
  19
  20 const DEFAULT_POOL_OPTIONS: ThreadPoolOptions = {
  21   enableEvents: true,
  22   restartWorkerOnError: true,
  23 };
  24
  25 export class WorkerSet extends WorkerAbstract<WorkerData> {
  26   public readonly emitter!: EventEmitter;
  27   private readonly workerSet: Set<WorkerSetElement>;
  28
  29   /**
  30    * Creates a new `WorkerSet`.
  31    *
  32    * @param workerScript -
  33    * @param workerOptions -
  34    */
  35   constructor(workerScript: string, workerOptions: WorkerOptions) {
  36     super(workerScript, workerOptions);
  37     this.workerOptions.poolOptions = {
  38       ...DEFAULT_POOL_OPTIONS,
  39       ...this.workerOptions.poolOptions,
  40     };
  41     this.workerSet = new Set<WorkerSetElement>();
  42     if (this.workerOptions.poolOptions?.enableEvents) {
  43       this.emitter = new EventEmitter();
  44     }
  45   }
  46
  47   get info(): SetInfo {
  48     return {
  49       version: WorkerConstants.version,
  50       type: 'set',
  51       worker: 'thread',
  52       size: this.size,
  53       elementsExecuting: [...this.workerSet].reduce(
  54         (accumulator, workerSetElement) => accumulator + workerSetElement.numberOfWorkerElements,
  55         0,
  56       ),
  57       elementsPerWorker: this.maxElementsPerWorker!,
  58     };
  59   }
  60
  61   get size(): number {
  62     return this.workerSet.size;
  63   }
  64
  65   get maxElementsPerWorker(): number | undefined {
  66     return this.workerOptions.elementsPerWorker;
  67   }
  68
  69   /** @inheritDoc */
  70   public async start(): Promise<void> {
  71     this.addWorkerSetElement();
  72     // Add worker set element sequentially to optimize memory at startup
  73     this.workerOptions.workerStartDelay! > 0 && (await sleep(this.workerOptions.workerStartDelay!));
  74   }
  75
  76   /** @inheritDoc */
  77   public async stop(): Promise<void> {
  78     for (const workerSetElement of this.workerSet) {
  79       const workerExitPromise = new Promise<void>((resolve) => {
  80         workerSetElement.worker.on('exit', () => {
  81           resolve();
  82         });
  83       });
  84       await workerSetElement.worker.terminate();
  85       await workerExitPromise;
  86     }
  87     this.workerSet.clear();
  88   }
  89
  90   /** @inheritDoc */
  91   public async addElement(elementData: WorkerData): Promise<void> {
  92     if (!this.workerSet) {
  93       throw new Error("Cannot add a WorkerSet element: workers' set does not exist");
  94     }
  95     const workerSetElement = await this.getWorkerSetElement();
  96     workerSetElement.worker.postMessage({
  97       event: WorkerMessageEvents.startWorkerElement,
  98       data: elementData,
  99     });
 100     ++workerSetElement.numberOfWorkerElements;
 101     // Add element sequentially to optimize memory at startup
 102     if (this.workerOptions.elementStartDelay! > 0) {
 103       await sleep(this.workerOptions.elementStartDelay!);
 104     }
 105   }
 106
 107   /**
 108    * Adds a new `WorkerSetElement`.
 109    */
 110   private addWorkerSetElement(): WorkerSetElement {
 111     const worker = new Worker(this.workerScript, {
 112       env: SHARE_ENV,
 113       ...this.workerOptions.poolOptions?.workerOptions,
 114     });
 115     worker.on(
 116       'message',
 117       this.workerOptions.poolOptions?.messageHandler ?? WorkerConstants.EMPTY_FUNCTION,
 118     );
 119     worker.on(
 120       'error',
 121       this.workerOptions.poolOptions?.errorHandler ?? WorkerConstants.EMPTY_FUNCTION,
 122     );
 123     worker.on('error', (error) => {
 124       this.emitter?.emit(WorkerSetEvents.error, error);
 125       if (this.workerOptions.poolOptions?.restartWorkerOnError) {
 126         this.addWorkerSetElement();
 127       }
 128     });
 129     worker.on(
 130       'online',
 131       this.workerOptions.poolOptions?.onlineHandler ?? WorkerConstants.EMPTY_FUNCTION,
 132     );
 133     worker.on(
 134       'exit',
 135       this.workerOptions.poolOptions?.exitHandler ?? WorkerConstants.EMPTY_FUNCTION,
 136     );
 137     worker.once('exit', () =>
 138       this.removeWorkerSetElement(this.getWorkerSetElementByWorker(worker)!),
 139     );
 140     const workerSetElement: WorkerSetElement = { worker, numberOfWorkerElements: 0 };
 141     this.workerSet.add(workerSetElement);
 142     return workerSetElement;
 143   }
 144
 145   private removeWorkerSetElement(workerSetElement: WorkerSetElement): void {
 146     this.workerSet.delete(workerSetElement);
 147   }
 148
 149   private async getWorkerSetElement(): Promise<WorkerSetElement> {
 150     let chosenWorkerSetElement: WorkerSetElement | undefined;
 151     for (const workerSetElement of this.workerSet) {
 152       if (workerSetElement.numberOfWorkerElements < this.workerOptions.elementsPerWorker!) {
 153         chosenWorkerSetElement = workerSetElement;
 154         break;
 155       }
 156     }
 157     if (!chosenWorkerSetElement) {
 158       chosenWorkerSetElement = this.addWorkerSetElement();
 159       // Add worker set element sequentially to optimize memory at startup
 160       this.workerOptions.workerStartDelay! > 0 &&
 161         (await sleep(this.workerOptions.workerStartDelay!));
 162     }
 163     return chosenWorkerSetElement;
 164   }
 165
 166   private getWorkerSetElementByWorker(worker: Worker): WorkerSetElement | undefined {
 167     let workerSetElt: WorkerSetElement | undefined;
 168     for (const workerSetElement of this.workerSet) {
 169       if (workerSetElement.worker.threadId === worker.threadId) {
 170         workerSetElt = workerSetElement;
 171         break;
 172       }
 173     }
 174     return workerSetElt;
 175   }
 176 }